For consumer appeal, a chocolate bar should have a very special consistency. It should snap brittly at room temperature but melt quickly in the mouth, where the temperature is about 35.degree. C. In warmer countries, for instance, it may, however, be difficult to maintain the texture of the chocolate up to the moment the chocolate is to be eaten. The problem then is to keep the brittleness of the chocolate without impairing its other properties.
By the use of various additives, sometimes combined with special processes of preparation, chocolate can be made to keep its texture also at temperatures at which it would otherwise have melted or at least softened excessively. Chocolate thus stabilised is referred to as heat-resistant or tropicalised chocolate.
Heat-resistant chocolate can be produced according to two fundamentally different methods.
In the first method, a certain amount of high-melting fat phase is added to the chocolate composition. The fat crystals in this phase then form a lattice that maintains its structure despite the melting of the remainder of the fatty phase. This method can be optimised, so as not to deteriorate the mouth feel of the chocolate.
In the second method, use is primarily made of the sugar particles in the chocolate mass to form a lattice that maintains its structure when the fatty phase melts. By adding water or other hydrophilic components, the sugar particles can be made to adhere to one another. When the chocolate bar is consumed, the sugar lattice is dissolved, there being no noticeable impairment of the mouth feel as compared with that of ordinary chocolate.
However, the problem associated with such a lattice of sugar particles resides in achieving a uniform, fine distribution of the water when preparing the chocolate. If one does not succeed in doing this, the sugar particles will form large aggregates making the chocolate mass gritty and too viscous, which may have negative effects on the consistency of the end product.
There are various known processes for finely distributing the water in the making of chocolate.
In one process, use is thus made of a water-in-oil emulsion consisting of triglyceride, emulsifier and water (or other hydrophilic additives). EP Patent Specification 0,033,718, for instance, discloses such a process.
Also, a protein-stabilised foam can be used for binding the water in the chocolate composition. EP Patent Application 407,347, for instance, discloses such a process.
In these prior-art processes, the emulsion or the foam is added to the chocolate mass, where it is broken, whereby the water is so distributed that the sugar particles will adhere to one another.
These processes all concern systems that require mechanical energy, such as homogenisation or mixing, to achieve the desired distribution of the water in the chocolate mass. In addition, these systems are not thermodynamically stable, i.e. they tend to separate sooner or later, which requires special process equipment. In addition, the admixture to the chocolate mass, as indeed the entire process, is difficult to perform in a controlled manner. Since it is difficult to foresee how the emulsion or the foam will be broken when admixed to the chocolate mass, it is difficult to control the effect of the water admixture.
The use of emulsions or foams is obviously disadvantageous owing to the size of the water domains in the systems. A water droplet in a water-in-oil emulsion may be from 0.1 .mu.m to 100 .mu.m in size. At the lower limit, a microemulsion is obtained, whereas the upper limit often involves rapid destabilisation of the system and phase separation. The water domains in foam lamellae may be relatively thin (in the order of below 1 .mu.m) but are instead extended in two dimensions. Too large water domains impart undesirable qualities to the chocolate.